1. Field of the Invention
The invention generally relates to a non-leaded package structure, and more particularly, to a quad or dual flat non-leaded package structure (QFN or DFN package structure) with protruded leads and a manufacturing method thereof.
2. Description of Related Art
Among the various packaging types in the semiconductor packaging industry, the flat packages such as quad or dual flat non-leaded (QFN or DFN) packages have the advantages of shorter signal transmission paths and relatively faster signal transmission speeds. Therefore, the QFN or DFN packages are quite suitable for chip packages with high-frequency signal transmission, for example, the radio-frequency band signals, and have become one of the mainstreams for the low-pin-count packages.
In the packaging processes of QFN or DFN packages, a plurality of chips are disposed on a leadframe. Then, each of the chips is electrically connected to the leadframe through a plurality of bonding wires. An encapsulant is formed to cover a portion of the leadframe, the bonding wires and the chips. Finally, the above-mentioned structure is singulated into a plurality of individual QFN or DFN package structures by a punch process or a sawing process.
In order to meet the users' requirements for higher capabilities of the small size chip packages, increasing the density of leads is usually attempted to achieve the required goal. However, it is restrained in increasing the number of leads of the leadframe commonly used in the QFN or DFN packages; hence, solutions to produce higher density of leads in the packages with the packaging technologies to fulfill the demand are eagerly pursued. Besides increasing the density of leads, to sustain the bonding strength between the leads and the encapsulant (mold locking) and to enhance the surface mount application ability and convenience for the QFN or DFN packages are also main concerns in packaging so as to increase the applicability thereof.